Add commandline option for strftime_format. Set check_updates in config because otherwise outdated fails since it isn't set even though there is a 'global'

Fix DeprecationWarning regarding invalid escape sequence. Fix SyntaxWarning regarding literal comparison.

Refactor of the standalone main loop to be sure that it take more or less refresh_time. Also add debug log to investigate some potential freeze during stats update or export

On Windows, fallback to %APPDATA% if %LOCALAPPDATA% doesn't exist.

- Remove duplicate code (one place to rule them all)
- Add SunOS support
- Add a safe function for creating a directory tree
- Put cache file in the cache directories

- wrong continued indentation
- missing whitespace after ':'
- unused imports
- expected 2 blank lines after class or function definition

Not so useful, one less import.

Update all affected imports accordingly.

Remove 'glances_' prefix from filenames.

Support remains there, but no system-wide configuration file will be
provided anymore.

Default configuration settings are initialized by code which may be
overridden by a configuration file.